Porous Co/Co–Ni–Pt nanostructures prepared by galvanic replacement towards methanol electro-oxidation

Abstract

The nanostructured Co/Co–Ni–Pt catalyst were synthesized by electrodeposition process and galvanic replacement reaction. The alloy prepared on a copper electrode (Cu/Co/Co–Ni–Zn) was dipped in platinum containing alkaline solution to produce a porous Cu/Co/Co–Ni–Pt catalyst. The catalyst was characterized by energy dispersive X-ray and scanning electron microscopy techniques and its electrocatalytic properties were evaluated using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques. The results showed that the Co/Co–Ni–Pt coatings are porous, and composed of discrete Pt nanoparticles with the crystallite size of about 66 nm. It was shown from cyclic voltammograms in alkaline solutions that the oxidation current of methanol on the nanostructured Cu/Co/Co–Ni–Pt electrode was much higher than that on flat platinum. Electrochemical impedance spectra on the Co/Co–Ni–Pt electrode reveal that the charge transfer resistance decreases with the increase of anodic potentials. All results show that the Co/Co–Ni–Pt catalysts can be potential anode catalysts for the direct methanol fuel cell.